This invention relates to regulators for conserving electrical energy in stores and office buildings. Such regulators have become increasingly popular over the last several years due to the continually rising cost of electrical energy. The problem is particularly acute for example, in supermarkets. They have many large electrical loads, such as refrigeration that simply cannot be turned off to reduce cost. Typically, supermarkets have a monthly electrical bill of several thousand dollars.
At the same time, many stores, such as supermarkets operate on a low profit margin. Thus, a definite need exists in those businesses for an electrical energy regulator which is both inexpensive and can still reduce power consumption wherever possible. In the prior art, several electrical energy controllers existed. However, these were often found to be not suitable solutions. Many of the prior art controllers are general purpose controllers. They are designed to control energy consumption in a wide variety of industries. Typically, they include a computer or other sophisticated and expensive hardware. But as a result, they are over designed for the task of controlling energy consumption in a single predefined manner. Thus, they are too costly for many businesses.
Other prior art energy controllers simply include a timer which opens and closes various relays at selectable times of the day. The relays in turn control the flow of electrical energy to various circuits in the store. This type of control is also deficient however, in that its control is not sensitive to weather conditions. For example, it does not allow various lights to be turned on or off depending upon whether it is a cloudy day or a sunny day. Further, the timer requires seasonal adjusting to compensate for changes in the hour of sunrise and sunset.
The prior art also includes photo electric operated controllers. These controllers do not have the deficiencies that are associated with timers as described above; but they are deficient in several other respects. For example all of the prior art photo electric controllers have the capability of sensing only a single level of light ambient intensity. Thus, their degree of control is limited. Further, they are all incapable of sensing levels of light intensity that occur after dusk. Thus, no energy saving steps can be carried out past dusk. As a result, stores are often over illuminated when it is dark outside. Customers come in from the dark outside with their irises wide open, yet the store lighting is at a level resembling daylight. This lighting inbalance not only wastes energy, but often is annoying to the customer.
Therefore, it is one object of the invention to provide a relatively inexpensive controller for regulating the consumption of electrical energy in a predetermined manner.
Another object of the invention is to provide a photo electric energy regulator which senses multiple levels of ambient light intensity to achieve an improved degree of control.
Another object of the invention is to provide a photo electric energy regulator for performing control functions at light intensity levels below those corresponding to dusk.
Still another object of the invention is to provide a photo electric energy controller which dims the interior lights after dusk to provide a close contrast with the exterior light intensity.